1. Field of the Invention
The invention relates generally to photovoltaic cells and methods of their manufacture, and more particularly to such cells employing thin film polymer electrolytes and methods of their manufacture.
2. Description of the Prior Art
Photovoltage or the photovoltaic effect may be defined as the conversion of light or electromagnetic photons to electrical energy by a material. Becquerel in 1839 was the first to discover that a photovoltage developed when light was shining on an electrode in an electrolyte solution. Nearly half a century elapsed before this effect was observed in a solid, namely in selenium. Again, many years passed before successful devices such as the photoelectric exposure meter, were developed. Radiation is absorbed in the neighborhood of a potential barrier, usually a pn junction or a metal-semiconductor contact or junction, giving rise to separate electron hole pairs which create a potential.
Photovoltaic cells have found numerous applications in electronics and aerospace, notably in satellites for instrument power, and powering communications apparatus in remote locations.
Intensive research in underway in the last decade to improve the production of these cells, e.g. (1) increasing the practical efficiency in order to approach the theoretical efficiency, (2) decreasing production costs, and (3) to find new materials and combinations.
Intensive interest in alternative energy sources and particularly in solar energy has increased because of political and economic impetus. Traditional sources of inexpensive energy are rapidly disappearing. Political instability, price/supply fixing by certain governments, and environmental concerns, dictate the search for new energy sources. Thus the present intense interest in solar energy. Each country has its own sunlight supply, and the United States has an ample supply. Ecologically, solar cells are a non-polluting clean source of energy. Solar energy in our forseeable future for many generations is limitless and non-depletable. One application of solar energy to which the present invention is directed is the direct conversion of electromagnetic radiation, particularly sunlight, to electricity.
Two of the classical goals of any photovoltaic cell are efficiency, and higher output voltage. Most prior art cells have a theoretical efficiency of about 25%. The cells of the present application approach 35%. The prior art voltage ranges from 0.2 to 0.5 volts per cell; the inventor's cells are approximately 0.625 volts.
Further, some prior art cells require that they be oriented so that the incident light is perpendicular to the face of the cell. In the present invention, while this is desirable, it is not essential, and they may operate at an angle from the perpendicular.
The present invention offers the possibility of ease of manufacture, attendant low cost, and manufacturing large surface areas with good quality and at a low cost.
The present invention is corrosion free. A reduction-oxidation couple in water has a photocorrosion resulting from an interaction between the water and semiconductors. The present invention by using a polymer matrix avoids photocorrosion and the attendant problems.
An object of the present invention is to provide a novel, double photoelectric cell for conversion of solar energy to electricity.
Another object of the invention is to provide a method for the manufacture of double photoelectrochemical cells. A further object of the invention is to provide a half-double photochemical cell for the conversion of solar energy to electricity using a thin film polymer electrolyte.
A further object of the invention is to provide a new family of photoelectrochemical cells having a theoretical higher output efficiency and output voltage than is available from single cells.
Another object of the invention is to provide cells which are easy to manufacture and are stable in operation.
These and other objects and features of the invention will be more fully understood from the description of the embodiments which follow, but it should be understood that the invention is not limited to these embodiments and may find application as would be obvious to a man skilled in the art following the teachings of this application.